1. Field of the Invention
This invention relates to computer data storage systems and, more particularly, to transporting pipe data between computer systems via Fibre Channel using shared SCSI devices.
2. Description of the Related Art
There is an increasing need for organizations to move large datasets efficiently between computer systems. For example, large backup datasets may be moved from a client computer system to a media server configured to store data for later retrieval, thereby protecting data from loss due to user error, system failure, outages, and disasters, etc. as well as archiving information for regulatory compliance, workflow tracking, etc. One common computer system arrangement that involves movement of large datasets from client computers to storage servers includes one or more client computers coupled to a storage area network (SAN). Conventional SANs may interconnect client systems with data storage appliances through a variety of high capacity physical links. One popular interconnect technology for such links is Fibre Channel. Fiber Channel is a set of standards based on high performance serial links and supporting several different higher-level protocols for controlling the movement of data. For instance, Fiber-Distributed Data Interface (FDDI), Small Computer System Interface (SCSI) device protocol, the High Performance Parallel Interface (HIPPI) protocol, the Intelligent Peripheral Interface (IPI) protocol, and other high-level protocol's are often mapped onto Fibre Channel's signaling and data transmission protocols. SCSI over Fibre Channel, sometimes referred to as Fibre Channel Protocol (FCP) has proven to be a popular and effective method of transferring SCSI data blocks between computer systems. In addition, the Fibre Channel architecture may be applied to multiple connection topologies including a single channel point-to-point link, a switched network, and/or an arbitrated loop topology.
Because the higher level protocols that are commonly supported by Fibre Channel do not support multiple concurrent data streams, currently available implementations may not reach the potential transfer speeds of the underlying Fibre Channel links. For example, the SCSI command set assumes packet delivery in accordance with standard sequential behavior. Once a connection is established between an initiator and a target device, any packet received from that initiator is assumed by the target device to be part of a single stream until the connection is ended. Accordingly, current SCSI over Fibre Channel implementations do not support transfer of multiple concurrent data streams on a single Fibre Channel link. In addition, while internet-style protocols such as TCP/IP or similar patterns do support multiple concurrent data streams, these protocols are not widely supported on Fibre Channel systems and require significant software processing to distinguish data streams and ensure data integrity. Even when standards become available for operating TCP/IP over Fibre Channel, these software processing steps may limit performance. As a result, there exists a need for systems and methods for interconnecting client computer systems and data storage devices that overcome the above limitations and make more efficient use of Fibre Channel's available physical bandwidth.